Experimental study on the space charge properties in haze events
Tianli Bo , Xiaobin Zhang , Sen Yang
DOI:10.1016/j.jes.2019.07.009
Received April 11, 2019,Revised , Accepted July 12, 2019, Available online July 22, 2019
Volume 32,2020,Pages 361-376
In recent years, haze has posed a serious threat to the global climate change, ecological balance and human health. In this study, the laboratory experiments and field observations were performed and a possible charging mechanism was proposed to investigate the space charge properties in haze events. The laboratory experiments showed that the charge polarity of primary aerosol is determined by species of combustion fuels while the magnitude is dependent on the combustion completeness. The field observations revealed that the space charge of atmosphere aerosol in haze events differs from that of fair weather and is closely related to PM2.5 concentration when Relative Humidity (RH) < 60%, with 1 to 2 orders of magnitude less than the case when RH ≥ 60%. The analysis of equivalent charge-to-mass ratio (ECTM) suggested that in haze events the space charge is governed by primary aerosol emitted by combustion of fossil fuel in a low relative humidity, whereas it is manipulated by the secondary chemical reaction of atmosphere aerosol in a high relative humidity. And we can identify the main pollutants in haze events according to the polarity of atmosphere aerosol and quickly take measures when RH < 60%. Accordingly, the dust-haze of RH < 80% can be divided into dry-dust-haze when RH < 60% and wet-dust-haze when 60% ≤ RH < 80%. Our study firstly elucidated the space charge properties of atmosphere aerosol in haze events and can provide a new perspective for the prevention and control of air pollution.
